Method for transmitting and receiving signal between terminal and base station in wireless communication system, and apparatus for supporting same

ABSTRACT

Disclosed are a method for transmitting and receiving a signal between a terminal and a base station in a wireless communication system and an apparatus for supporting the same. More particularly, disclosed is an explanation for a method of transmitting and receiving a signal between a terminal and a base station according to a new HARQ procedure which differs from a Hybrid Automatic Repeat reQuest (HARQ) procedure supported in a conventional wireless communication system.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore particularly, to a method of transmitting and receiving a signalbetween a terminal and a base station in a wireless communication systemand apparatus for supporting the same.

More specifically, the present disclosure is directed to a method oftransmitting and receiving a signal between a terminal and a basestation based on a new hybrid automatic repeat request (HARQ) proceduredifferent from that supported in the conventional wireless communicationsystem.

BACKGROUND ART

Wireless access systems have been widely deployed to provide varioustypes of communication services such as voice or data. In general, thewireless access system means a multiple access system that supportscommunication between multiple users by sharing available systemresources (bandwidth, transmission power, etc.). For example, multipleaccess systems include a Code Division Multiple Access (CDMA) system, aFrequency Division Multiple Access (FDMA) system, a Time DivisionMultiple Access (TDMA) system, an Orthogonal Frequency Division MultipleAccess (OFDMA) system, and a Single Carrier Frequency Division MultipleAccess (SC-FDMA) system.

As a number of communication devices have required higher communicationcapacity, the necessity for mobile broadband communication much improvedthan the existing radio access technology (RAT) has increased. Inaddition, massive machine type communications (MTC) capable of providingvarious services anytime and anywhere by connecting a number of devicesor things to each other has been considered in the next generationcommunication system. Moreover, a communication system design capable ofsupporting services/UEs sensitive to reliability and latency has alsobeen discussed.

The introduction of next generation RAT considering the enhanced mobilebroadband communication, massive MTC, ultra-reliable and low latencycommunication (URLLC), etc. has been discussed.

DISCLOSURE Technical Problem

The object of the present disclosure is to provide a method by which aterminal and a base station transmit and receive acknowledgement (ACK)information for a received signal in a wireless communication system.

Specifically, the object of the present disclosure is to provide amethod capable of transmitting and receiving ACK information on a codeblock group (CBG) basis rather than on a transmission (or transport)block (TB) basis as in the conventional wireless communication system.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

The present disclosure provides a method of transmitting and receiving asignal between a terminal (user equipment) and a base station in awireless communication system and apparatuses therefor.

In an aspect of the present disclosure, provided herein is a method oftransmitting and receiving a signal to and from a base station (BS) by auser equipment (UE) in a wireless communication system. The method mayinclude receiving, from the BS, a signal composed of at least one codeblock group (CBG) and transmitting, to the BS, acknowledgement (ACK)information for each CBG, wherein the ACK information includes aplurality of numbers of bit information.

In another aspect of the present disclosure, provided herein is a methodof transmitting and receiving a signal to and from a UE by a BS in awireless communication system. The method may include transmitting, tothe UE, a signal composed of at least one CBG and receiving, from theUE, ACK information for each CBG, wherein the ACK information includes aplurality of numbers of bit information.

In still another aspect of the present disclosure, provided herein is aUE for transmitting and receiving a signal to and from a BS in awireless communication system. The UE may include a transmitter, areceiver, and a processor connected to the transmitter and the receiver.The processor may be configured to receive, from the BS, a signalcomposed of at least one CBG and transmit, to the BS, ACK informationfor each CBG, wherein the ACK information includes a plurality ofnumbers of bit information.

In a further aspect of the present disclosure, provided herein is a BSfor transmitting and receiving a signal to and from a UE in a wirelesscommunication system. The BS may include a transmitter, a receiver, anda processor connected to the transmitter and the receiver. The processormay be configured to transmit, to the UE, a signal composed of at leastone CBG and receive, from the UE, ACK information for each CBG, whereinthe ACK information includes a plurality of numbers of bit information.

Each CBG may comprise at least one code block (CB). The plurality ofnumbers of the bit information may indicate any one of the followingstates: one state for indicating ACK and N states for indicatingnon-acknowledgement (NACK).

In this case, each of the N states may indicate any combination of atleast one of: (A) first information indicating whether a number of CBswhere NACK occurs in a corresponding CBG is greater than or equal to apredetermined value and whether, when the number of CBs where NACKoccurs is greater than or equal to the predetermined value, there areconsecutive CBs among the CBs where NACK occurs; (B) second informationindicating a location region including the CBs where NACK occurs in thecorresponding CBG; (C) third information indicating a range includingthe ratio of the CBs where NACK occurs to whole CBs included in thecorresponding CBG; and (D) fourth information indicating aretransmission method preferred by the UE for the corresponding CBG.

The first information may indicate one of: (A-1) information indicatingthat the number of CBs where NACK occurs in the corresponding CBG issmaller than or equal to the predetermined value; (A-2) informationindicating that the number of CBs where NACK occurs in the correspondingCBG is greater than the predetermined value and the CBs where NACKoccurs are not consecutive; and (A-3) information indicating that thenumber of CBs where NACK occurs in the corresponding CBG is greater thanthe predetermined value and the consecutive CBs are present among theCBs where NACK occurs.

The second information may indicate one of: (B-1) information indicatingthat among first and second CBGs obtained by dividing the correspondingCBG in half, the first CBG includes at least one CB where NACK occurs;(B-2) information indicating that among the first and second CBGsobtained by dividing the corresponding CBG in half, the second CBGincludes at least one CB where NACK occurs; and (B-3) informationindicating that both the first and second CBGs obtained by dividing thecorresponding CBG in half include at least one CB where NACK occurs.

The third information may indicate one of: (C-1) information indicatingthat the ratio of the CBs where NACK occurs to the whole CBs included inthe corresponding CBG is smaller than or equal to a first threshold;(C-2) information indicating that the ratio of the CBs where NACK occursto the whole CBs included in the corresponding CBG is greater than thefirst threshold and smaller than or equal to a second threshold; and(C-3) information indicating that the ratio of the CBs where NACK occursto the whole CBs included in the corresponding CBG is greater than thesecond threshold.

The fourth information may indicate one of: (D-1) information indicatingthat the retransmission method preferred by the UE for the correspondingCBG is an incremental redundancy (IR) type; and (D-2) informationindicating that the retransmission method preferred by the UE for thecorresponding CBG is a chase combining (CC) type.

When some CBs in the received signal composed of the at least one CBGare dropped by the BS, the UE may further receive information on thedropped CBs from the BS.

In this case, the UE may determine the N states by excluding the droppedCBs from counting or assuming the dropped CBs as ACK.

The UE may further receive, from the BS, a response message in responseto the ACK information for each CBG.

The response message may comprise retransmission of whole CBs includedin a CBG reported by the UE as NACK or retransmission of several CBsincluded in the CBG reported by the UE as NACK.

When some CBs in the received signal composed of the at least one CBGare dropped by the BS, the response message may comprise retransmissionof the several CBs included in a CBG reported by the UE as NACK.

When some CBs in the received signal composed of the at least one CBGare dropped by the BS, if the UE transmits, to the BS, ACK for CBGsexcept the some CBGs after receiving information on the some CBs fromthe BS, the response message may include the several CBs.

The UE may further transmit, to the BS, ACK information for at least oneCBG included in the response message.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

Advantageous Effects

As is apparent from the above description, the embodiments of thepresent disclosure have the following effects.

According to the present disclosure, a UE and a BS can transmit andreceive ACK information for each CBG in a TB with a larger size than theconventional TB. In addition, the UE and BS can retransmit a specific CBor a specific CBG based on the ACK information.

In particular, since a plurality of pieces of bit information is used totransmit NACK for the specific CBG, the UE and BS can obtain moredetails from the NACK and thus perform retransmission based on thedetails more properly.

The above-described aspects of the present disclosure are merely a partof preferred embodiments of the present disclosure. Those skilled in theart will derive and understand various embodiments reflecting thetechnical features of the present disclosure from the following detaileddescription of the present disclosure.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure, provide embodiments of the presentdisclosure together with detail explanation. Yet, a technicalcharacteristic of the present disclosure is not limited to a specificdrawing. Characteristics disclosed in each of the drawings are combinedwith each other to configure a new embodiment. Reference numerals ineach drawing correspond to structural elements.

FIG. 1 is a diagram illustrating physical channels and a signaltransmission method using the physical channels;

FIG. 2 is a diagram illustrating exemplary radio frame structures;

FIG. 3 is a diagram illustrating an exemplary resource grid for theduration of a downlink slot;

FIG. 4 is a diagram illustrating an exemplary structure of an uplinksubframe;

FIG. 5 is a diagram illustrating an exemplary structure of a downlinksubframe;

FIG. 6 is a diagram illustrating a self-contained subframe structureapplicable to the present disclosure;

FIGS. 7 and 8 are diagrams illustrating representative methods forconnecting TXRUs to antenna elements;

FIG. 9 is a diagram schematically illustrating a hybrid beamformingstructure from the perspective of transceiver units (TXRUs) and physicalantennas according to an embodiment of the present disclosure;

FIG. 10 is a diagram schematically illustrating beam sweeping operationfor synchronization signals and system information in a downlink (DL)transmission process according to an embodiment of the presentdisclosure;

FIG. 11 is a diagram schematically illustrating a cyclic redundancycheck (CRC) configuration for each CB in one TB applicable to thepresent disclosure;

FIG. 12 is a diagram illustrating a method of displaying CRC decodingresults and CRC-bad causes;

FIGS. 13 to 15 are diagrams illustrating CRC decoding result scenariosaccording to the present disclosure;

FIG. 16 is a diagram schematically illustrating a signal transmissionand reception procedure between a BS and a UE;

FIG. 17 is a diagram illustrating a signal transmission and receptionmethod between a UE and a BS applicable to the present disclosure; and

FIG. 18 is a diagram illustrating the configurations of a UE and a BSfor implementing the proposed embodiments.

BEST MODE

The embodiments of the present disclosure described below arecombinations of elements and features of the present disclosure inspecific forms. The elements or features may be considered selectiveunless otherwise mentioned. Each element or feature may be practicedwithout being combined with other elements or features. Further, anembodiment of the present disclosure may be constructed by combiningparts of the elements and/or features. Operation orders described inembodiments of the present disclosure may be rearranged. Someconstructions or elements of any one embodiment may be included inanother embodiment and may be replaced with corresponding constructionsor features of another embodiment.

In the description of the attached drawings, a detailed description ofknown procedures or steps of the present disclosure will be avoided lestit should obscure the subject matter of the present disclosure. Inaddition, procedures or steps that could be understood to those skilledin the art will not be described either.

Throughout the specification, when a certain portion “includes” or“comprises” a certain component, this indicates that other componentsare not excluded and may be further included unless otherwise noted. Theterms “unit”, “-or/er” and “module” described in the specificationindicate a unit for processing at least one function or operation, whichmay be implemented by hardware, software or a combination thereof. Inaddition, the terms “a or an”, “one”, “the” etc. may include a singularrepresentation and a plural representation in the context of the presentdisclosure (more particularly, in the context of the following claims)unless indicated otherwise in the specification or unless contextclearly indicates otherwise.

In the embodiments of the present disclosure, a description is mainlymade of a data transmission and reception relationship between a BaseStation (BS) and a User Equipment (UE). A BS refers to a terminal nodeof a network, which directly communicates with a UE. A specificoperation described as being performed by the BS may be performed by anupper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with a UE may be performed by the BS, or network nodesother than the BS. The term ‘BS’ may be replaced with a fixed station, aNode B, an evolved Node B (eNode B or eNB), gNode B (gNB), an AdvancedBase Station (ABS), an access point, etc.

In the embodiments of the present disclosure, the term terminal may bereplaced with a UE, a Mobile Station (MS), a Subscriber Station (SS), aMobile Subscriber Station (MSS), a mobile terminal, an Advanced MobileStation (AMS), etc.

A transmission end is a fixed and/or mobile node that provides a dataservice or a voice service and a reception end is a fixed and/or mobilenode that receives a data service or a voice service. Therefore, a UEmay serve as a transmission end and a BS may serve as a reception end,on an UpLink (UL). Likewise, the UE may serve as a reception end and theBS may serve as a transmission end, on a DownLink (DL).

The embodiments of the present disclosure may be supported by standardspecifications disclosed for at least one of wireless access systemsincluding an Institute of Electrical and Electronics Engineers (IEEE)802.xx system, a 3rd Generation Partnership Project (3GPP) system, a3GPP Long Term Evolution (LTE) system, 3GPP 5G NR system and a 3GPP2system. In particular, the embodiments of the present disclosure may besupported by the standard specifications, 3GPP TS 36.211, 3GPP TS36.212, 3GPP TS 36.213, 3GPP TS 36.321, 3GPP TS 36. 331, 3GPP TS 38.211,3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321 and 3GPP TS 38.331. Thatis, the steps or parts, which are not described to clearly reveal thetechnical idea of the present disclosure, in the embodiments of thepresent disclosure may be explained by the above standardspecifications. All terms used in the embodiments of the presentdisclosure may be explained by the standard specifications.

Reference will now be made in detail to the embodiments of the presentdisclosure with reference to the accompanying drawings. The detaileddescription, which will be given below with reference to theaccompanying drawings, is intended to explain exemplary embodiments ofthe present disclosure, rather than to show the only embodiments thatcan be implemented according to the disclosure.

The following detailed description includes specific terms in order toprovide a thorough understanding of the present disclosure. However, itwill be apparent to those skilled in the art that the specific terms maybe replaced with other terms without departing the technical spirit andscope of the present disclosure.

For example, the term, TxOP may be used interchangeably withtransmission period or Reserved Resource Period (RRP) in the same sense.Further, a Listen-Before-Talk (LBT) procedure may be performed for thesame purpose as a carrier sensing procedure, clear channel assessment(CCA), channel access procedure (CAP), for determining whether a channelstate is idle or busy.

Hereinafter, 3GPP LTE/LTE-A systems are explained, which are examples ofwireless access systems.

The embodiments of the present disclosure can be applied to variouswireless access systems such as Code Division Multiple Access (CDMA),Frequency Division Multiple Access (FDMA), Time Division Multiple Access(TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), SingleCarrier Frequency Division Multiple Access (SC-FDMA), etc.

CDMA may be implemented as a radio technology such as UniversalTerrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented asa radio technology such as Global System for Mobile communications(GSM)/General packet Radio Service (GPRS)/Enhanced Data Rates for GSMEvolution (EDGE). OFDMA may be implemented as a radio technology such asIEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Evolved UTRA(E-UTRA), etc.

UTRA is a part of Universal Mobile Telecommunications System (UMTS).3GPP LTE is a part of Evolved UMTS (E-UMTS) using E-UTRA, adopting OFDMAfor DL and SC-FDMA for UL. LTE-Advanced (LTE-A) is an evolution of 3GPPLTE. While the embodiments of the present disclosure are described inthe context of a 3GPP LTE/LTE-A system in order to clarify the technicalfeatures of the present disclosure, the present disclosure is alsoapplicable to an IEEE 802.16e/m system, etc.

1. 3GPP LTE/LTE-A System

1.1. Physical Channels and Signal Transmission and Reception MethodUsing the Same

In a wireless access system, a UE receives information from an basestation on a DL and transmits information to the base station on a UL.The information transmitted and received between the UE and the basestation includes general data information and various types of controlinformation. There are many physical channels according to thetypes/usages of information transmitted and received between the basestation and the UE.

FIG. 1 illustrates physical channels and a general signal transmissionmethod using the physical channels, which may be used in embodiments ofthe present disclosure.

When a UE is powered on or enters a new cell, the UE performs initialcell search (S11). The initial cell search involves acquisition ofsynchronization to an base station. Specifically, the UE synchronizesits timing to the base station and acquires information such as a cellIdentifier (ID) by receiving a Primary Synchronization Channel (P-SCH)and a Secondary Synchronization Channel (S-SCH) from the base station.

Then the UE may acquire information broadcast in the cell by receiving aPhysical Broadcast Channel (PBCH) from the base station.

During the initial cell search, the UE may monitor a DL channel state byreceiving a Downlink Reference Signal (DL RS).

After the initial cell search, the UE may acquire more detailed systeminformation by receiving a Physical Downlink Control Channel (PDCCH) andreceiving a Physical Downlink Shared Channel (PDSCH) based oninformation of the PDCCH (S12).

To complete connection to the base station, the UE may perform a randomaccess procedure with the base station (S13 to S16). In the randomaccess procedure, the UE may transmit a preamble on a Physical RandomAccess Channel (PRACH) (S13) and may receive a PDCCH and a PDSCHassociated with the PDCCH (S14). In the case of contention-based randomaccess, the UE may additionally perform a contention resolutionprocedure including transmission of an additional PRACH (S15) andreception of a PDCCH signal and a PDSCH signal corresponding to thePDCCH signal (S16).

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the base station (S17) and transmit a Physical Uplink SharedChannel (PUSCH) and/or a Physical Uplink Control Channel (PUCCH) to thebase station (S18), in a general UL/DL signal transmission procedure.

Control information that the UE transmits to the base station isgenerically called Uplink Control Information (UCI). The UCI includes aHybrid Automatic Repeat and reQuest Acknowledgement/NegativeAcknowledgement (HARQ-ACK/NACK), a Scheduling Request (SR), a ChannelQuality Indicator (CQI), a Precoding Matrix Index (PMI), a RankIndicator (RI), etc.

In the LTE system, UCI is generally transmitted on a PUCCH periodically.However, if control information and traffic data should be transmittedsimultaneously, the control information and traffic data may betransmitted on a PUSCH. In addition, the UCI may be transmittedaperiodically on the PUSCH, upon receipt of a request/command from anetwork.

1.2. Resource Structure

FIG. 2 illustrates exemplary radio frame structures used in embodimentsof the present disclosure.

FIG. 2(a) illustrates frame structure type 1. Frame structure type 1 isapplicable to both a full Frequency Division Duplex (FDD) system and ahalf FDD system.

One radio frame is 10 ms (Tf=307200·Ts) long, including equal-sized 20slots indexed from 0 to 19. Each slot is 0.5 ms (Tslot=15360≠Ts) long.One subframe includes two successive slots. An ith subframe includes2ith and (2i+1)th slots. That is, a radio frame includes 10 subframes. Atime required for transmitting one subframe is defined as a TransmissionTime Interval (TTI). Ts is a sampling time given as Ts=1/(15kHz×2048)=3.2552×10−8 (about 33 ns). One slot includes a plurality ofOrthogonal Frequency Division Multiplexing (OFDM) symbols or SC-FDMAsymbols in the time domain by a plurality of Resource Blocks (RBs) inthe frequency domain.

A slot includes a plurality of OFDM symbols in the time domain. SinceOFDMA is adopted for DL in the 3GPP LTE system, one OFDM symbolrepresents one symbol period. An OFDM symbol may be called an SC-FDMAsymbol or symbol period. An RB is a resource allocation unit including aplurality of contiguous subcarriers in one slot.

In a full FDD system, each of 10 subframes may be used simultaneouslyfor DL transmission and UL transmission during a 10-ms duration. The DLtransmission and the UL transmission are distinguished by frequency. Onthe other hand, a UE cannot perform transmission and receptionsimultaneously in a half FDD system.

The above radio frame structure is purely exemplary. Thus, the number ofsubframes in a radio frame, the number of slots in a subframe, and thenumber of OFDM symbols in a slot may be changed.

FIG. 2(b) illustrates frame structure type 2. Frame structure type 2 isapplied to a Time Division Duplex (TDD) system. One radio frame is 10 ms(Tf=307200·Ts) long, including two half-frames each having a length of 5ms (=153600·Ts) long. Each half-frame includes five subframes each being1 ms (=30720·Ts) long. An ith subframe includes 2ith and (2i+1)th slotseach having a length of 0.5 ms (Tslot=15360·Ts). Ts is a sampling timegiven as Ts=1/(15 kHz×2048)=3.2552×10−8 (about 33 ns).

A type-2 frame includes a special subframe having three fields, DownlinkPilot Time Slot (DwPTS), Guard Period (GP), and Uplink Pilot Time Slot(UpPTS). The DwPTS is used for initial cell search, synchronization, orchannel estimation at a UE, and the UpPTS is used for channel estimationand UL transmission synchronization with a UE at an base station. The GPis used to cancel UL interference between a UL and a DL, caused by themulti-path delay of a DL signal.

Table 1 below lists special subframe configurations (DwPTS/GP/UpPTSlengths).

TABLE 1 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Normal Extended Normal Extended Special subframecyclic prefix cyclic prefix cyclic prefix cyclic prefix configurationDwPTS in uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) 2192· T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 ·T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600· T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592· T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 ·T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —

In the LTE Rel-13 system, it is newly added that the configuration of aspecial subframe (e.g., the lengths of DwPTS/GP/UpPTS) is established byconsidering the number of additional SC-FDMA symbols, X, which isprovided by the higher layer parameter named “srs-UpPtsAdd” (if theparameter is not configured, X is set to 0). In the LTE Rel-14 system,specific subframe configuration #10 is newly added. The UE is notexpected to be configured with 2 additional UpPTS SC-FDMA symbols forspecial subframe configurations {3, 4, 7, 8} for normal cyclic prefix indownlink and special subframe configurations {2, 3, 5, 6} for extendedcyclic prefix in downlink and 4 additional UpPTS SC-FDMA symbols forspecial subframe configurations {1, 2, 3, 4, 6, 7, 8} for normal cyclicprefix in downlink and special subframe configurations {1, 2, 3, 5, 6}for extended cyclic prefix in downlink.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Normal Extended Normal Extended Special subframecyclic prefix cyclic prefix cyclic prefix cyclic prefix configurationDwPTS in uplink in uplink DwPTS in uplink in uplink 0  6592 · T_(s) (1 +X) · 2192 · T_(s) (1 + X) · 2560 · T_(s)  7680 · T_(s) (1 + X) · 2192 ·T_(s) (1 + X) · 2560 · T_(s) 1 19760 · T_(s) 20480 · T_(s) 2 21952 ·T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680· T_(s) (2 + X) · 2192 · T_(s) (2 + X) · 2560 · T_(s) 5  6592 · T_(s)(2 + X) · 2192 · T_(s) (2 + X) · 2560 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — — 10 13168 · T_(s) 13152 · T_(s) 12800 · T_(s) — — —

FIG. 3 illustrates an exemplary structure of a DL resource grid for theduration of one DL slot, which may be used in embodiments of the presentdisclosure.

Referring to FIG. 3, a DL slot includes a plurality of OFDM symbols inthe time domain. One DL slot includes 7 OFDM symbols in the time domainand an RB includes 12 subcarriers in the frequency domain, to which thepresent disclosure is not limited.

Each element of the resource grid is referred to as a Resource Element(RE). An RB includes 12×7 REs. The number of RBs in a DL slot, NDLdepends on a DL transmission bandwidth.

FIG. 4 illustrates a structure of a UL subframe which may be used inembodiments of the present disclosure.

Referring to FIG. 4, a UL subframe may be divided into a control regionand a data region in the frequency domain. A PUCCH carrying UCI isallocated to the control region and a PUSCH carrying user data isallocated to the data region. To maintain a single carrier property, aUE does not transmit a PUCCH and a PUSCH simultaneously. A pair of RBsin a subframe are allocated to a PUCCH for a UE. The RBs of the RB pairoccupy different subcarriers in two slots. Thus it is said that the RBpair frequency-hops over a slot boundary.

FIG. 5 illustrates a structure of a DL subframe that may be used inembodiments of the present disclosure.

Referring to FIG. 5, up to three OFDM symbols of a DL subframe, startingfrom OFDM symbol 0 are used as a control region to which controlchannels are allocated and the other OFDM symbols of the DL subframe areused as a data region to which a PDSCH is allocated. DL control channelsdefined for the 3GPP LTE system include a Physical Control FormatIndicator Channel (PCFICH), a PDCCH, and a Physical Hybrid ARQ IndicatorChannel (PHICH).

The PCFICH is transmitted in the first OFDM symbol of a subframe,carrying information about the number of OFDM symbols used fortransmission of control channels (i.e. the size of the control region)in the subframe. The PHICH is a response channel to a UL transmission,delivering an HARQ ACK/NACK signal. Control information carried on thePDCCH is called Downlink Control Information (DCI). The DCI transportsUL resource assignment information, DL resource assignment information,or UL Transmission (Tx) power control commands for a UE group.

2. New Radio Access Technology System

As more and more communication devices have required highercommunication capacity, the necessity for the mobile broadbandcommunication much improved than the existing RAT has increased. Inaddition, massive machine type communications (MTC) capable of providingvarious services anytime and anywhere by connecting a number of devicesor things has also been considered. Moreover, a communication systemdesign capable of supporting services/UEs sensitive to reliability andlatency has been proposed.

The introduction of new RAT considering the enhanced mobile broadbandcommunication, massive MTC, ultra-reliable and low-latency communication(URLLC), etc. has been discussed. In the present disclosure, thecorresponding technology is referred to as new RAT or new radio (NR) forsimplicity.

2.1. Numerologies

The NR system to which the present disclosure is applicable supportsvarious OFDM numerologies as shown in Table 3 below. The value of μ andcyclic prefix information per carrier bandwidth part can be signaled forDL and UL, respectively. For example, the value of u and cyclic prefixinformation for DL carrier bandwidth part may be signaled though higherlayer signaling such as DL-BWP-mu and DL-MWP-cp. As another example, thevalue of μ and cyclic prefix information for UL carrier bandwidth partmay be signaled though higher layer signaling such as UL-BWP-mu andUL-MWP-cp.

TABLE 3 μ Δf = 2^(μ) · 15[kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

2.2. Frame Structure

DL and UL transmission are configured with frames each having a lengthof 10 ms. Each frame may include 10 subframes, each having a length of 1ms. In this case, the number of consecutive OFDM symbols in eachsubframe is N_(symb) ^(subframe,μ)=N_(symb) ^(slot)N_(slot)^(subframe,μ).

Each frame may include two half-frames with the same size. In this case,the two half-frames may include subframes 0 to 4 and subframes 5 to 9,respectively.

Regarding the subcarrier spacing μ, slots may be numbered within onesubframe in ascending order as follows: n_(s) ^(μ)∈{0, . . . , N_(slot)^(subframe,μ)−1} and may also be numbered within a frame in ascendingorder as follow: N_(s,f) ^(μ)∈{0, . . . , N_(slot) ^(frame,μ)−1}. Inthis case, the number of consecutive OFDM symbols in one slot (N_(symb)^(slot)) may be determined as shown in Tables 4 and 5 below according tothe cyclic prefix. The start slot (n_(s) ^(μ)) of a subframe is alignedwith the start OFDM symbol (n_(s) ^(μ)N_(symb) ^(slot)) of thecorresponding subframe in the time domain. Table 4 shows the number ofOFDM symbols in each slot/frame/subframe in the case of a normal cyclicprefix, and Table 5 shows the number of OFDM symbols in eachslot/frame/subframe in the case of an extended cyclic prefix.

TABLE 4 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16 5 14 320 32

TABLE 5 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) NN_(slot) ^(subframe, μ)2 12 40 4

The NR system to which the present disclosure is applicable may employ aself-contained slot structure as the above-described slot structure.

FIG. 6 is a diagram illustrating a self-contained subframe structureapplicable to the present disclosure.

In FIG. 6, the hatched region (e.g., symbol index=0) represents a DLcontrol region, and the black region (e.g., symbol index=13) representsan UL control region. The other region (e.g., symbol index=1 to 12) maybe used for DL data transmission or for UL data transmission.

Based on the self-contained slot structure, a BS and a UE maysequentially perform DL transmission and UL transmission in one slot.That is, the BS and UE may transmit and receive not only DL data butalso UL ACK/NACK for the DL data in one slot. The self-contained slotstructure may reduce a time required for data retransmission when a datatransmission error occurs, thereby minimizing the latency of the finaldata transmission.

In the self-contained slot structure, a time gap with a predeterminedlength is required to allow the BS and UE to switch from transmissionmode to reception mode or vice versa. To this end, some OFDM symbols atthe time of switching from DL to UL may set as a guard period (GP).

Although it is described that the self-contained slot structure includesboth the DL and UL control regions, these control regions may beselectively included in the self-contained slot structure. In otherwords, the self-contained slot structure according to the presentdisclosure may include either the DL control region or the UL controlregion as well as both the DL and UL control regions as shown in FIG. 6.

For example, a slot may have various slot formats. In this case, OFDMsymbols in each slot can be classified into a DL symbol (denoted by‘D’), a flexible symbol (denoted by ‘X’), and a UL symbol (denoted by‘U’).

Thus, a UE may assume that DL transmission occurs only in symbolsdenoted by ‘D’ and ‘X’ in a DL slot. Similarly, the UE may assume thatUL transmission occurs only in symbols denoted by ‘U’ and ‘X’ in a ULslot.

2.3. Analog Beamforming

In a millimeter wave (mmW) system, since a wavelength is shortened, aplurality of antenna elements may be installed in the same area. Thatis, considering that the wavelength at 30 GHz band is 1 cm, a total of100 antenna elements can be installed in a 5*5 cm panel at intervals of0.5 lambda (wavelength) in the case of a 2-dimensional array. Therefore,in the mmW system, it is possible to improve the coverage or throughputby increasing the beamforming (BF) gain using multiple antenna elements.

In this case, each antenna element can include a transceiver unit (TXRU)to enable adjustment of transmit power and phase per antenna element. Bydoing so, each antenna element can perform independent BF per frequencyresource.

However, installing TXRUs in all of the about 100 antenna elements isless feasible in terms of cost. Therefore, a method of mapping aplurality of antenna elements to one TXRU and adjusting the direction ofa beam using an analog phase shifter has been considered. However, thismethod is disadvantageous in that frequency selective BF is impossiblebecause only one beam direction is generated over the full band.

To solve this problem, as an intermediate form of digital BF and analogBF, hybrid BF with B TXRUs that are fewer than Q antenna elements can beconsidered. In the case of the hybrid BF, the number of beam directionsthat can be transmitted at the same time is limited to B or less, whichdepends on how B TXRUs and Q antenna elements are connected.

FIGS. 7 and 8 are diagrams illustrating representative methods forconnecting TXRUs to antenna elements. Here, the TXRU virtualizationmodel represents the relationship between TXRU output signals andantenna element output signals.

FIG. 7 shows a method for connecting TXRUs to sub-arrays. In FIG. 7, oneantenna element is connected to one TXRU.

Meanwhile, FIG. 8 shows a method for connecting all TXRUs to all antennaelements. In FIG. 8, all antenna element are connected to all TXRUs. Inthis case, separate addition units are required to connect all antennaelements to all TXRUs as shown in FIG. 8.

In FIGS. 7 and 8, W indicates a phase vector weighted by an analog phaseshifter. That is, W is a major parameter determining the direction ofthe analog BF. In this case, the mapping relationship between CSI-RSantenna ports and TXRUs may be 1:1 or 1-to-many.

The configuration shown in FIG. 7 has a disadvantage in that it isdifficult to achieve BF focusing but has an advantage in that allantennas can be configured at low cost.

On the contrary, the configuration shown in FIG. 8 is advantageous inthat BF focusing can be easily achieved. However, since all antennaelements are connected to the TXRU, it has a disadvantage of high cost.

When a plurality of antennas is used in the NR system to which thepresent disclosure is applicable, the hybrid BF obtained by combiningthe digital BF and analog BF may be applied. In this case, the analog BF(or radio frequency (RF) BF) means an operation of performing precoding(or combining) at the RF stage. In the hybrid BF, precoding (orcombining) is performed at each of the baseband stage and RF stage,respectively. Thus, the hybrid beamforming is advantageous in that itcan guarantee performance similar to the digital BF while reducing thenumber of RF chains and the number of D/A (digital-to-analog) (or A/D(analog-to-digital) converters.

For convenience of description, a hybrid BF structure may be representedby N transceiver units (TXRUs) and M physical antennas. In this case,digital BF for L data layers to be transmitted by a transmission end maybe represented by an N-by-L matrix. Thereafter, N converted digitalsignals are converted into analog signals by the TXRUs, and then analogBF, which is represented by an M-by-N matrix, is applied the convertedsignals.

FIG. 9 is a diagram schematically illustrating a hybrid beamformingstructure from the perspective of TXRUs and physical antennas accordingto an embodiment of the present disclosure. In FIG. 9, the number ofdigital beams is L and the number of analog beams is N.

Additionally, to provide more efficient BF to UEs located in a specificarea, a method of designing a BS capable of changing analog BF on asymbol basis has been considered in the NR system to which the presentdisclosure is applicable. Further, the NR system to which the presentdisclosure is applicable has considered the introduction of a pluralityof antenna panels to which independent hybrid BF is applicable bydefining N specific TXRUs and M RF antennas as one antenna panel asillustrated in FIG. 9.

When a BS uses a plurality of analog beams as described above, each UEhas a different analog beam suitable for signal reception. Thus, the NRsystem to which the present disclosure is applicable has considers thebeam sweeping operation where a BS transmits signals (at leastsynchronization signals, system information, paging, etc.) by applying adifferent analog beam to each symbol within a specific subframe (SF) sothat all UEs may have reception opportunities.

FIG. 10 is a diagram schematically illustrating beam sweeping operationfor synchronization signals and system information in DL transmissionprocess according to an embodiment of the present disclosure.

In FIG. 10, a physical resource (or channel) for transmitting systeminformation of the NR system to which the present disclosure isapplicable in a broadcasting manner is referred to as an xPBCH. In thiscase, analog beams belonging to different antenna panels may besimultaneously transmitted in one symbol.

In addition, to measure a channel for each analog beam, the introductionof a beam reference signal (BRS), which is a reference signal (RS) towhich a single analog beam (corresponding to a specific antenna panel)is applied, has been discussed in the NR system to which the presentdisclosure is applicable. The BRS may be defined for a plurality ofantenna ports, and each BRS antenna port may correspond to a singleanalog beam. In this case, in contrast to the BRS, all analog beams inan analog beam group may be applied to a synchronization signal or xPBCHto assist a random UE to correctly receive the synchronization signal orxPBCH.

3. Proposed Embodiments

Hereinafter, the configurations according to the present disclosure willbe described in detail based on the above-described technical features.

In the NR system to which the present disclosure is applicable, it isexpected that due to the use of eMBB, the maximum size of a transportblock (TB) may increase several times or more compared to that of thelegacy LTE system. In addition, compared to the prior art, the number ofcode blocks (CBs) included in each TB may increase by several times ormore. As a result, the conventional hybrid automatic repeat request(HARQ) operation, which is performed for each TB and requiresretransmission of all CBs included in the TB, may become inefficient.

In addition, if data for URLLC, which requires very short latency, isoverridden to have a higher priority while eMBB transmission isperformed, the HARQ for each TB may not be suitable.

Moreover, considering a time-selective interference scenario where aninterference signal from a neighboring cell may be power boosted by apencil beam (e.g., an antenna pattern with a narrow main lobe, where thecontour line of a radiation pattern approximates to a circle) in adynamic time division duplex (TDD) environment, the HARQ for each TB maybecome more inefficient.

Therefore, a method of performing HARQ for each codeword block group(CBG) or CB included in a TB is considered in the NR system, instead ofperforming the HARQ for each TB.

For example, one TB, which is composed of N CBs, may include G CBGs. Inthis case, each CBG may be composed of B or B′ CBs. B′ indicates thenumber of CBs included in the last CBG, and the value of B′ may be equalto or different from B depending on the values of N and G.

FIG. 11 is a diagram schematically illustrating a cyclic redundancycheck (CRC) configuration for each CB in one TB applicable to thepresent disclosure.

As shown in FIG. 11, a CRC (CB-CRC) may be inserted in each CB in bothstructures A and B. However, structure B is different from structure Ain that a CRC (CBG-CRC) is additionally inserted in each CBG.

In structures A and B, one TB is composed of G CBGs, and a CRC (TB-CRC)for the one RB may be inserted.

Each of the CB-CRC, CBG-CRC and TB-CRC may be configured to have adifferent size (e.g., length). In structure B, the CBG-CRC of a G-th CBGmay be omitted, or it may have a different size from those of otherCBGs.

FIG. 12 is a diagram illustrating a method of displaying CRC decodingresults and CRC-bad causes. Herein, ‘CRC-bad’ may mean that the resultof a CRC at a receiving end is different from that intended by atransmitting end when the transmitting end inserts a CRC parity bit. Ingeneral, the transmitting and receiving ends comply with rulesdetermined thereby. Specifically, the receiving end (e.g., a UE) mayperform the CRC in order to determine whether a rule intended by thetransmitting end is maintained after decoding of a data block. In thefollowing, ‘CRC-good’ means that the decoding result indicates that theintention (or rule) of inserting the CRC parity bit is not changedbetween the transmitting and receiving ends, whereas ‘CRC-bad’ meansthat the decoding result indicates that the intention (or rule) ofinserting the CRC parity bit is changed between the transmitting andreceiving ends.

In FIG. 12, the first block indicates a CB where ‘CRC-good’ occurs, andeach of the second to fourth blocks indicates a CB where ‘CRC-bad’occurs.

Specifically, the second block indicates a CB where a CB decoding erroroccurs due to an insufficient signal-to-noise ratio (SNR). In general,even when link adaptation is applied, a decoding error may occur in someCBs (about 1 to 10%) in a fading environment (e.g., attenuationdifference, phase difference, etc.).

The third block indicates a CB where the CB decoding error occurs beforeor after the corresponding CB due to degradation of inter-slot channelestimation performance when some CBs are punctured due to time-selectiveinterference or URLLC transmission. The CRC-bad occurrence probabilitymay be higher than the about 1 to 10% CB error probability in the normalfading environment (however, it may be lower than a CB error probabilitydue to time-selective interference, which will be described later).

The fourth block indicates a CB where the CB decoding error occurs whensome CBs are punctured due to the time-selective interference or URLLCtransmission. In the case of CB puncturing, the CB error probabilityincreases to 100%, and in the case of the time-selective interference,the CB error probability may be much higher than the CB errorprobability caused by the above-described inter-slot channel estimationperformance degradation.

FIGS. 13 to 15 are diagrams illustrating CRC decoding result scenariosaccording to the present disclosure. Although the CB-CRC, CBG-CRC andTB-CRC are not illustrated in FIGS. 13 to 15 for clarity, the presentdisclosure can be applied when at least one of the CB-CRC, CBG-CRC andTB-CRC is included in some embodiments.

The CRC decoding state and CRC-bad cause for each CB illustrated inFIGS. 13 to 15 may be interpreted with reference to FIG. 12.

FIG. 13 illustrates a CRC decoding result scenario where the number ofCBs included in the CBG is greater than that of FIG. 15. In contrast toFIG. 13, FIG. 14 illustrates a CRC decoding result scenario where arelatively small number of CBs are included in the last CBG of the TB.Unlike FIG. 13, FIG. 15 illustrates a CRC decoding result scenario wherea small number of CBs are included in each CBG of the TB.

The CRC-bad occurrence scenario shown in FIG. 13 may be divided asfollows.

(1) Type (A-2)˜Type (A-3)

-   -   NACK occurs for some non-consecutive CBs (e.g., g2 and g5) in a        g-th CBG.    -   When a UE or a gNB fails to receive an RS included in some        non-consecutive CBs (e.g., g2 and g5) in the g-th CBG,        additional CRC-bad occurs due to degradation of cross-slot        channel estimation performance for CBs g1, g3 and g4, which are        adjacent to CBs g2 and g5.    -   NACK occurs for some consecutive CBs (e.g., g2 to g5) in the        g-th CBG.    -   When a UE or a gNB fails to receive an RS included in some        consecutive CBs (e.g., g2 to g5) in the g-th CBG, additional        CRC-bad occurs due to degradation of cross-slot channel        estimation performance for CBs g1 and g6, which are adjacent to        CBs g2 to g5.

(2) Type (A-4)˜Type (A-5)

-   -   NACK occurs for some consecutive CBs (e.g., g1 to g4) in the        g-th CBG.    -   When a UE or a gNB fails to receive an RS included in some        consecutive CBs (e.g., g1 to g4) in the g-th CBG, additional        CRC-bad occurs due to degradation of cross-slot channel        estimation performance for the last CB, CB g8 of a (g-1)-th CBG        and CB g5 of the g-th CBG, which are adjacent to CBs g1 to g4.    -   NACK occurs for some consecutive CBs over the (g-1)-th and g-th        CBGs.    -   When a UE or a gNB fails to receive an RS included in some        consecutive CBs across the (g-1)-th and g-th CBGs, additional        CRC-bad occurs in some CBs adjacent thereto.

In summary, CRC-bad may occur in the following cases:

1) When NACK occurs for some non-consecutive CBs in a CBG;

2) When NACK occurs for some consecutive CBs in a CBG; and

3) When NACK occurs for consecutive CBs across consecutive CBGs.

Unlike FIG. 13, FIG. 14 illustrates that the number of CBs in the lastCBG of the TB is different from that those of other CBGs.

Unlike FIGS. 12 and 13, FIG. 15 illustrates that CRC-bad occurs in CBsacross three consecutive CBGs or more.

In summary, the CRC-bad occurrence based on the CBG level, which isillustrated in FIGS. 13 to 15, may be classified into the followingthree types in terms of the CB.

[1] NACK for some non-consecutive CBs in a CBG

[2] NACK for some consecutive CBs in a CBG

[3] NACK for consecutive CBs across consecutive CBGs

FIG. 16 is a diagram schematically illustrating a signal transmissionand reception procedure between a BS and a UE. In FIG. 16, it is assumedthat one TB is transmitted by the BS and received by the UE.

The multi-level ACK/NACK reporting method proposed in the presentdisclosure may be different from the conventional one used in the legacyLTE system in terms of not only ACK/NACK reporting but also DCIconfiguration and retransmission. In particular, the configuration andinterpretation of a multi-level ACK/NACK field for a CBG transmittedduring initial TB transmission may be different from those of amulti-level ACK/NACK field for a retransmitted CB or CBG.

In FIG. 16, initial TB transmission is performed at time (A). In thiscase, it is assumed that a TB is composed of G CBGs and each CBG iscomposed of B CBs. In addition, it is assumed that the UE obtains thetransport block size (TBS) of the corresponding TB and the values of Gand B from DCI transmitted by the BS.

Hereinafter, a description will be given of how the BS and UE operate attimes (B), (C), (D), (E), and (F) of FIG. 16 when the multi-levelACK/NACK method according to the present disclosure is applied.

3.1. CBG-Level ACK/NACK Reporting (at Time (B) of FIG. 16)

The UE completes decoding of G CBG and reports ACK/NACK for each CBG tothe BS.

In this case, a NACK report may have the following various states byreflecting the CRC-bad type of a corresponding CBG. A k-bit ACK/NACKfield may have 2^(k) states, and the 2^(k) states may include one statefor indicating ACK and (2^(k)−1) states for indicating various NACKreasons.

In the present disclosure, it is assumed that the value of k is 2.However, when the value of k is greater than 2, various NACK states maybe defined in a similar way as described below.

Hereinafter, a method of distinguishing between NACK states will bedescribed in detail.

3.1.1. First Method (Method of Distinguishing Between NACK forConsecutive CBs in CBG)

-   -   NACK state 0: NACK occurs for X CBs or less.    -   NACK state 1: NACK occurs for (X+1) CBs or more, and the        corresponding CBs are not consecutive.    -   NACK state 2: NACK occurs for (X+1) CBs or more, and the        corresponding CBs are consecutive.

The value of X may be predefined in 3GPP specifications or configuredcell-commonly or UE-specifically and (semi-) statically or dynamically.Alternatively, when the value of X is not separately configured, X mayhave a default value of 1.

The first method may be modified as follows.

-   -   NACK state 0: NACK does not continuously occur for X consecutive        CBs    -   NACK state 1: NACK continuously occurs for X consecutive CBs    -   NACK state 2: Reserved

3.1.2. Second Method (Method of Identifying Whether NACK CBs in CBG areConsecutive and Distinguishing Between Positions of Consecutive CBs)

-   -   NACK state 0: NACK occurs for some of the CBs from a        ceil(B/2)-th CB to a (B-1)-th CB or consecutive CBs thereamong.    -   NACK state 1: NACK occurs for some of the CBs from a 0-th CB to        a (ceil(B/2)−1)-th CB or consecutive CBs thereamong.    -   NACK state 2: (i) NACK occurs for all CBs, or (ii) NACK occurs        for some of the CBs from the 0-th CB to the (ceil(B/2)−1)-th CB        or consecutive CBs thereamong and NACK occurs for some of the        CBs from the ceil(B/2)-th CB to the (B-1)-th CB or consecutive        CBs thereamong.

In other words, NACK state 2 means a state including both NACK state 0and NACK state 1. Here, ceil(A) is a function of finding the smallestinteger from among integers equal to or greater than A. For example,ceil (4.3)=5.

3.1.3. Third Method (Method of Distinguishing Between Ratios of NACK CBsin CBG)

-   -   NACK state 0: NACK occurs for X % CBs or less.    -   NACK state 1: NACK occurs for Y % CBs or less but more than X %        CBs.    -   NACK state 2: NACK occurs for more than Y % CBs.

Here, the values of X and Y may be predefined in 3GPP specificationssuch that the values are determined based on at least one of the TBS orthe value of G or B. Alternatively, the values of X and Y may beconfigured cell-commonly or UE-specifically and (semi-) statically ordynamically. Alternatively, when the values of X and Y are notseparately configured, X and Y may have default values predefined in3GPP specifications.

Additionally, when X is equal to Y, NACK state 1 may be reserved forother purposes.

The first method |[01] may be modified as follows.

-   -   NACK state 0: The number of NACK CBs are equal to or less than X        % of the total CBs.    -   NACK state 1: The number of NACK CBs are more than X % of the        total CBs.    -   NACK state 2: Reserved

3.1.4. Fourth Method (Method of Distinguishing Between CBGRetransmission Schemes)

-   -   NACK state 0: Request for incremental redundancy (IR) type        retransmission    -   NACK state 1: Request for chase combining (CC) type        retransmission    -   NACK state 2: Reserved

In the fourth method, the IR and CC may mean the following operations.

-   -   IR: Scheduling request for a redundancy version (RV) having a        non-zero value (for a parity bit) or a data (coded bit) portion        corresponding to an RV different from the RV indicated by        previous scheduling    -   CC: Scheduling request for an RV having a zero value (for a        systematic bit) or a data (coded bit) portion corresponding to        an RV equal to the RV indicated by previous scheduling

The above-described first to fourth methods may be combined forimplementation. More particularly, they may be combined in a randommanner. For example, the following combination examples may be appliedto distinguish between NACK states.

Combination Example #1

-   -   NACK state 0: NACK does not continuously occur for X consecutive        CBs.    -   NACK state 1: NACK continuously occurs for X consecutive CBs,        and IR-type retransmission is requested.    -   NACK state 2: NACK continuously occurs for X consecutive CBs,        and CC-type retransmission is requested.

Combination Example #2

-   -   NACK state 0: NACK occurs for X % CBs or less.    -   NACK state 1: NACK occurs for more than X % CBs, and IR-type        retransmission is requested    -   NACK state 2: NACK occurs for more than X % CBs, and CC-type        retransmission is requested.

When NACK states are configured with multiple levels as described above,the UE may report a CRC-bad type for each CBG or a representative valueof CRC-bad types for the entirety of one TB.

In the former case, a k-bit ACK/NACK state field is allocated to eachCBG, and thus a total of (k*G) bits may be allocated for entire HARQ-ACKfeedback.

In the latter case, HARQ-ACK feedback may be configured as follows.Assuming that the total number of CBGs is G, (i) a 1 bit for indicatingonly ACK or NACK may be allocated for each CBG, and (ii) k bits forindicating which state of the above-described NACK states (a total of2^(k) states) is the representative state for all CBGs may be allocated.As a result, the HARQ-ACK feedback may be composed of a total of (G+k)bits.

In this case, reporting the NACK state for each CBG may be advantageousin that the NACK state for each CBG is accurately reported but has adisadvantage in that the payload size of ACK/NACK reporting increases.

On the other hand, reporting the representative NACK state for theentire TB may be disadvantageous in that it is difficult to accuratelyreport the NACK state for each state but has an advantage in that thepayload size of ACK/NACK reporting is reduced.

In this case, the following methods may be applied to select therepresentative NACK state for the entire TB.

For example, the UE may determine NACK states in each CBG where NACKoccurs according to each of the methods, set the NACK state mostfrequently appearing in the TB as the representative NACK state for theentirety of the TB, and then report the corresponding NACK state.

As another example, if there is at least one CBG with a specific NACKstate (e.g., state X), the UE may set NACK state X as the representativevalue for multiple CBGs. If there is no

CBG corresponding to NACK state X, the UE may set another NACK state(e.g., state Y) as the representative value for the multiple CBGs. Forinstance, in the first and third method, NACK states 1 and 0 may bedetermined as states X and Y, respectively.

Whether the UE reports the NACK state for each CBG or the representativevalue for the TB in order to preforming HARQ ACK/NACK reporting may bepredefined through association with the value of G (the number of CBGs)in 3GPP specifications. Alternatively, it may be configured by the BScell-commonly or UE-specifically and (semi-) statically or dynamically.

As a particular example, when the BS drops transmission of some CBs (forexample, some CBs may be dropped due to URLLC transmission), the BS maytransmit to the UE information indicating that the corresponding CBs aredropped. If the UE obtains information indicating that the CBs aredropped before a specific time (Q) from the time when the UE reports ULACK/ACK for received data in which the corresponding CBs are supposed tobe included, the UE may perform HARQ ACK/NACK reporting according to thefollowing options.

[Option 1] In the case of multi-level ACK/NACK, dropped CBs are excludedin distinguishing between NACK states.

(A) When X NACK CBs are counted according to the first method, thedropped CBs are not counted.

(B) In the second method, the dropped CBs are assumed to be ACK.

(C) When X % and Y % are calculated according to the third method, thedropped CBs are excluded from counting the total number of CBs and thenumber of NACK CBs.

(D) When the third method |[02] is applied, the retransmission type(e.g., IR or CC) is determined by considering only NACK CBs except thedropped CBs. This may be applied when the above-described methods arecombined. For example, the UE may distinguish between NACK stateswithout consideration of the dropped CBs.

[Option 2] In the case of single-level ACK/NACK, dropped CBs areexcluded.

-   -   When reporting ACK/NACK for a CBG, the UE assumes the dropped CB        as an ACK CB.

[Option 3] When remaining CBs except dropped CBs in a specific CBG areall ACK CBs, the UE reports the corresponding CBGs as ACK.

In this case, the specific time Q may be predefined depending on UEcategory in 3GPP specifications or configured by the BS cell-commonly orUE-specifically and (semi-) statically or dynamically.

3.2. CBG Retransmission (at Time (C) of FIG. 16)

Based on the CBG-level ACK/NACK and multi-level NACK state reported bythe UE, the BS may perform retransmission as follows.

(1) Retransmission of all CBGs reported as NACK

(2) Retransmission of all CBs included in some of the CBGs reported asNACK

(3) Retransmission of some CBs included in some of the CBGs reported asNACK

In this case, since configuration (2) includes configuration (1),examples of distinguishing between configurations (2) and (3) will bedescribed. That is, it is assumed that the BS retransmits all CBsincluded in a NACK CBG or some CBs included in the NACK CBG.

Although the BS retransmits all CBs in the NACK CBG in general, the BSmay retransmit some CBs of the NACK CBG in the following specific cases.

1) A case where the BS does not transmit some CBs in the correspondingCBG to transmit data with a relatively high priority such as URLLC, etc.

2) A case where the BS desires to transmit some CBs since the number ofCBs included in the CBG, B is much greater than the number of resourcesavailable for retransmission

3) When the code rate of a CB transmitted at a specific time (e.g.,slot) is higher than those of other CBs since an additional signal(e.g., synchronization signal or CSI-RS) is transmitted at the specifictime during the initial TB transmission and when a CBG to which thecorresponding CB belongs is reported as NACK, the BS may retransmit theCB with the higher code rate preferentially.

4) A case in which the BS is capable of estimating that CRC-bad occursonly in few CBs in the corresponding CBG based on the reportedmulti-level NACK state

5) A case in which the BS is capable of estimating that NACK occurs forconsecutive CBGs and CRC-bad occurs only in few CBs in the first andlast CBGs among the consecutive NACK CBGs based on the reportedmulti-level NACK state

In this case, the BS may inform the UE through DCI whether the BSschedules the retransmission of all CBs included in the NACK CBG (on aCBG basis) or the retransmission of some CBs included in the NACK CBG(on a CBG basis). Alternatively, it may be automatically determined byUE's HARQ-ACK feedback.

In the latter case, if the number of NACK CBGs is less than or equal toa specific value, the BS may schedule the retransmission on a CB basis.On the contrary, if the number of NACK CBGs is more than the specificvalue, the BS may schedule the retransmission on a CBG basis.

In addition, the configuration of DCI, which is transmitted by the BS,may vary depending on whether the BS retransmits all or some CBsincluded in the NACK CBG.

Moreover, the ACK/NACK reporting method and payload configuration forthe retransmission may vary depending on whether the BS retransmits theentirety of a CBG or some CBs. In particular, differences between theACK/NACK reporting method and payload configuration for theretransmission and those for the initial transmission may be explicitlyindicated by DCI at the CBG retransmission time. Alternatively, theACK/NACK reporting method for the retransmission and the ACK/NACKreporting method for the initial transmission may be separatelypredefined in 3GPP specifications. Further, they may be configured bythe BS cell-commonly or UE-specifically and (semi-) statically ordynamically. Additionally, the ACK/NACK reporting method and payloadconfiguration for the CBG retransmission may be configured differentlydepending on retransmission times (e.g., (D) and (F) of FIG. 16).

3.3. ACK/NACK Reporting on CBG Retransmission (at Time (D) of FIG. 16)

The UE reports the CBG-level ACK/NACK and multi-level NACK state at time(B) of FIG. 16, receives retransmission in response to the transmittedreport at time (C), and then reports ACK/NACK for a retransmitted CBG orsome retransmitted CBs at time (D) again.

If the retransmission at time (C) corresponds to retransmission of allCBs included in a specific CBG, the UE may perform ACK/NACK reportingusing the same method as that used for reporting the CBG-level ACK/NACKand multi-level NACK state at time (B). However, in this case, thefollowing options may be further applied. That is, the options mayinclude configuring a payload such that ACK/NACK is reported for onlythe retransmitted CBG or all CBs in the initial TB.

On the other hand, if the retransmission at time (C) corresponds toretransmission of some CBs included in a CBG, a CB where CRC-bad occurs(hereinafter, such a CB is referred to as a CRC-bad CB) in a NACK CBGreported at time (B) may not be included in the CBs retransmitted attime (C). Thus, the BS and UE may differently interpret NACK during theACK/NACK reporting procedure, which is performed at time (D).

First, the following classification may be established depending on howthe CRC-bad CBs reported at time (B) are included in the CBsretransmitted at time (C).

(1) All of the CRC-bad CBs at time (B) are included in the CBsretransmitted at time (C).

(2) None of the CRC-bad CBs at time (B) are included in the CBsretransmitted at time (C).

(3) Some the CRC-bad CBs at time (B) are included in the CBsretransmitted at time (C).

However, the BS may not determine, based on the CBG-level ACK/NACKreport at time (D), which one of the following three scenarios is thecause that the CBs retransmitted at time (C) are reported as CBG NACK attime (D).

-   -   Whether the retransmitted CBs are still NACK CBs after combining        although the retransmitted CBs include the CRC-bad CBs at time        (B)    -   Whether the retransmitted CBs are different from the CRC-bad CBs        at time (B)    -   Whether the corresponding CBG is a NACK CBG since the        retransmitted CBs include only some of the CRC-bad CBs at time        (B)

As a result, the BS may not determine how to select CBs to beretransmitted at time (E).

To solve this problem, the present disclosure proposes the followingmethod.

First, the UE maintains the ACK/NACK reporting method at time (D) to beequal to the CBG-level ACK/NACK reporting method at time (B), the UE mayuse a multi-level NACK state field for a CBG that is not retransmittedat time (C) as a field for indicating the decoding result of each CBincluded in the CBG retransmitted at time (C) during the ACK/NACKreporting at time (D).

Here, since the multi-level NACK state may mean a field for providingadditional information on a CBG where NACK occurs as described insection 3.1, information on the multi-level NACK state for the CBG,which is not retransmitted at time (C), is not required. As a result,the corresponding field may be used to represent in further detail theCRC-bad type of the CBG to which the CBs retransmitted at time (C)belong. The expression of “further detail” may be defined as follows.

1) A relationship between the CBs retransmitted at time (C) and theCRC-bad CBs at time (B): In this case, information on the relationshipmay contain one of the following items.

-   -   Whether all of the CRC-bad CBs at time (B) are included in the        CBs retransmitted at time (C)    -   Whether none of the CRC-bad CBs at time (B) are included in the        CBs retransmitted at time (C)    -   Whether some the CRC-bad CBs at time (B) are included in the CBs        retransmitted at time (C)

2) A method of informing whether each of the CBs retransmitted at time(C) is a CRC-good CB or a CRC-bad CB using single-level ACK/NACK

In this case, the UE may independently report the CRC decoding result ofeach of the retransmitted CBs or the CRC decoding results of all CBs(including the retransmitted CBs and CBs that are not retransmitted) inthe CBG to which the retransmitted CBs belong.

3.4. CBG Retransmission (at Time (E) of FIG. 16)

At time (E), the BS may retransmit all CBs in a specific CBG, some CBsin the specific CBG, or CBs including or except the CBs retransmitted attime (C) based on the ACK/NACK reported at time (D) in a similar way asdescribed in section 3.2. In addition, the BS may retransmit, at time(E), the CBs or CBG that is not retransmitted at time (C) regardless ofthe ACK/NACK report at time (D). Then, the UE may use the same method asdescribed in section 3.3 to perform ACK/NACK reporting at time (E).

The above-described ACK/NACK method may be applied not only to ACK/NACKreporting for DL transmission but also to ACK/NACK reporting for ULtransmission. Accordingly, when a UE performs initial TB transmissionand TB retransmission, a BS may perform ACK/NACK reporting according tothe above-described methods.

In addition, the methods described with reference to (B) to (E) of FIG.16 may be applied either independently or in combination.

Moreover, the CBG-level ACK/NACK, multi-level ACK/NACK, and single-levelACK/NACK may be independent from each other. That is, each of them maybe independently used at each time.

Further, the multi-level ACK/NACK technique proposed in the presentdisclosure is not limited to ACK/NACK reporting on a CBG basis. That is,the multi-level ACK/NACK technique can be applied when ACK/NACK isreported on a TB basis. Specifically, a UE or a BS may performmulti-level ACK/NACK reporting by distinguishing between NACK states fora plurality of TBs with multiple levels.

FIG. 17 is a diagram illustrating a signal transmission and receptionmethod between a UE and a BS according to the present disclosure. Morespecifically, FIG. 17 shows that the BS (base station, e.g., eNB or gNB)transmits a signal and the UE receives an ACK signal for the receivedsignal (that is, the BS and the UE correspond to a transmitting node anda receiving node, respectively). However, in some embodiments, the BSand UE operations illustrated in FIG. 17 may be reversed. In otherwords, a UE may operate as a receiving node and a BS may operate as atransmitting node. In the following, it is assumed that a BS operates asa transmitting node and a UE operates as a receiving node.

First, a BS 100 transmits to a UE 1 a signal (e.g., first signal)composed of at least one CBG (S1710). In this case, each CBG maycomprise at least one CB.

Next, the UE 1 determines ACK information for the signal (e.g., firstsignal) received in step S1710 (S1720). According to an embodiment ofthe present disclosure, when the UE 1 determines that NACK occurs for aspecific CBG, the UE may determine a particular NACK state for thespecific CBG.

For example, the UE 1 may determine whether the number of CBs where NACKoccurs in the corresponding CBG is greater than or equal to apredetermined value. When the number of CBs where NACK occurs is greaterthan or equal to the predetermined value, the UE may determine theparticular NACK state for the specific CBG based on whether there areconsecutive CBs among the CBs where NACK occurs.

As another example, the UE 1 may determine the particular NACK state forthe specific CBG based on a location region in which the CBs where NACKoccurs in the corresponding CBG are present.

As still another example, the UE 1 may determine the particular NACKstate for the specific CBG based on a ratio of the CBs where NACK occursto whole CBs included in the corresponding CBG.

As a further example, the UE 1 may determine the particular NACK statefor the specific CBG based on a retransmission method preferred by theUE for the corresponding CBG.

Thereafter, the UE 1 transmits, to the BS 100, the ACK informationdetermined in step S1720 using a plurality of numbers of bit information(S1730).

In this case, the plurality of numbers of the bit information mayindicate any one of the following states: one state for indicating ACK;and N states for indicating NACK, where N may be a natural number largerthan 1.

Each of the N states may indicate any combination of at least one of:(A) first information indicating whether the number of CBs where NACKoccurs in the corresponding CBG is greater than or equal to thepredetermined value and whether, when the number of CBs where NACKoccurs is greater than or equal to the predetermined value, theconsecutive CBs are present among the CBs where NACK occurs; (B) secondinformation indicating the location region in which the CBs where NACKoccurs in the corresponding CBG are present; (C) third informationindicating a range including the ratio of the CBs where NACK occurs tothe whole CBs included in the corresponding CBG; and (D) fourthinformation indicating the retransmission method preferred by the UE forthe corresponding CBG.

More specifically, the first to fourth information may indicate thefollowing particular information.

The first information may indicate one of: (A-1) information indicatingthat the number of CBs where NACK occurs in the corresponding CBG issmaller than or equal to the predetermined value; (A-2) informationindicating that the number of CBs where NACK occurs in the correspondingCBG is greater than the predetermined value and the CBs where NACKoccurs are not consecutive; and (A-3) information indicating that thenumber of CBs where NACK occurs in the corresponding CBG is greater thanthe predetermined value and the consecutive CBs are present among theCBs where NACK occurs.

The second information may indicate one of: (B-1) information indicatingthat among first and second CBGs obtained by dividing the correspondingCBG in half, the first CBG includes at least one CB where NACK occurs;(B-2) information indicating that among the first and second CBGsobtained by dividing the corresponding CBG in half, the second CBGincludes at least one CB where NACK occurs; and (B-3) informationindicating that both the first and second CBGs obtained by dividing thecorresponding CBG in half include at least one CB where NACK occurs.

The third information may indicate one of: (C-1) information indicatingthat the ratio of the CBs where NACK occurs to the whole CBs included inthe corresponding CBG is smaller than or equal to a first threshold;(C-2) information indicating that the ratio of the CBs where NACK occursto the whole CBs included in the corresponding CBG is greater than thefirst threshold and smaller than or equal to a second threshold; and(C-3) information indicating that the ratio of the CBs where NACK occursto the whole CBs included in the corresponding CBG is greater than thesecond threshold.

The fourth information may indicate one of: (D-1) information indicatingthat the retransmission method preferred by the UE for the correspondingCBG is an incremental redundancy (IR) type; and (D-2) informationindicating that the retransmission method preferred by the UE for thecorresponding CBG is a chase combining (CC) type.

Additionally, although not shown in FIG. 17, when several CBs in thereceived signal composed of the at least one CBG are dropped by the BS100, the UE 1 may receive information on the dropped CBs from the BS100.

In this case, the UE 1 may determine the N states by excluding thedropped CBs from counting or assuming the dropped CBs as ACK in stepS1720.

The BS 100 may determine a retransmission signal based on a secondsignal received from the UE 1 (S1740) and then transmit theretransmission signal (third signal) to the UE 1 (S1750).

The third signal may comprise retransmission of whole CBs included in aCBG reported by the UE 1 as NACK in step S1730 or retransmission ofseveral CBs included in the CBG reported by the UE 1 as NACK in stepS1730.

More specifically, when the BS 100 drops several CBs in the first signalto transmit service data with a relatively high priority such as URLLC,the BS 100 may retransmit, to the UE 1, the several CBs included in theCBG reported by the UE 1 as NACK.

In addition, when the BS 100 intentionally drops the several CBs andprovides information on the dropped CBs to the UE 1 directly orindirectly, the UE 1 may report a CBG including the corresponding CBs asACK. In this case, the BS 100 may also transmit the dropped CB s in theCBGs in a selective manner.

The reason for why the UE 1 does not assume the dropped CBs as NACK evenif the UE 1 obtains the information on the CBs dropped by the BS 100 maybe that (1) the UE 1 correctly receives the information indicating thatthe several CBs are dropped (if the UE fails to detect the information,the corresponding CBs should be reported as NACK) and (2) the UE 1interprets all CBs in the CBG except the dropped CBs as ACK.

The UE 1 may transmit ACK information (fourth signal) for at least oneCBGs included in the third signal to the BS 100 (S1760). In this case,the ACK information for the third signal may be configured andtransmitted in a similar way as that for the first signal.

Since each of the examples of the proposed methods may be included asone method for implementing the present disclosure, it is apparent thateach example can be regarded as a proposed method. In addition, althoughthe proposed methods can be implemented independently, some of theproposed methods can be combined (or merged) for implementation.Moreover, it may be regulated that information on whether the proposedmethods are applied (or information on rules related to the proposedmethods) should be transmitted from a BS to a UE through a predefinedsignal (e.g., a physical layer signal, a higher layer signal, etc.).

4. Device Configuration

FIG. 18 is a diagram illustrating the configurations of a UE and a BSfor implementing the proposed embodiments. The UE and the BS illustratedin FIG. 18 are implemented to perform the embodiments of the signaltransmission and reception method between a BS and a UE.

The UE 1 may act as a transmission end in UL and a reception end in DL.The BS (eNB or gNB) 100 may act as a reception end in UL and atransmission end in DL.

Each of the UE and BS may include a transmitter 10/110 and a receiver20/120 for controlling transmission and reception of information, data,and/or messages and an antenna 30/130 for transmitting and receivinginformation, data, and/or messages.

In addition, each of the UE and BS may include a processor 40/140 forimplementing the above-described embodiments of the present disclosureand a memory 50/150 for temporarily or permanently storing operations ofthe processor 40/140.

With the above configuration, the UE 1 receives a signal composed of atleast one CBGs from the BS 100 through the receiver 20 and transmits ACKinformation including a plurality of numbers of bit information for eachCBG to the BS 100 through the transmitter 10.

The BS 100 transmits a signal composed of at least one CBGs to the UE 1through the transmitter 110 and receives ACK information including aplurality of numbers of bit information for each CBG through thereceiver 120.

Each CBG may be composed of at least one CB. The plurality of numbers ofthe bit information may indicate any one of the following states: onestate for indicating ACK; and N states for indicating NACK, where N maybe a natural number larger than 1.

Each of the N states may indicate any combination of at least one of:(A) first information indicating whether the number of CBs where NACKoccurs in a corresponding CBG is greater than or equal to apredetermined value and whether, when the number of CBs where NACKoccurs is greater than or equal to the predetermined value, there areconsecutive CBs among the CBs where NACK occurs; (B) second informationindicating a location region in which the CBs where NACK occurs in thecorresponding CBG are present; (C) third information indicating a rangeincluding the ratio of the CBs where NACK occurs to whole CBs includedin the corresponding CBG; and (D) fourth information indicating aretransmission method preferred by the UE for the corresponding CBG.

The transmitter and receiver of each of the UE and BS may perform packetmodulation/demodulation for data transmission, high-speed packet channelcoding, OFDMA packet scheduling, TDD packet scheduling, and/or channelmultiplexing. Each of the UE and BS of FIG. 18 may further include alow-power Radio Frequency (RF)/Intermediate Frequency (IF) module.

Meanwhile, the UE may be any of a Personal Digital Assistant (PDA), acellular phone, a Personal Communication Service (PCS) phone, a GlobalSystem for Mobile (GSM) phone, a Wideband Code Division Multiple Access(WCDMA) phone, a Mobile Broadband System (MB S) phone, a hand-held PC, alaptop PC, a smart phone, a Multi Mode-Multi Band (MM-MB) terminal, etc.

The smart phone is a terminal taking the advantages of both a mobilephone and a PDA. It incorporates the functions of a PDA, that is,scheduling and data communications such as fax transmission andreception and Internet connection into a mobile phone. The MB-MMterminal refers to a terminal which has a multi-modem chip built thereinand which can operate in any of a mobile Internet system and othermobile communication systems (e.g. CDMA 2000, WCDMA, etc.).

Embodiments of the present disclosure may be achieved by various means,for example, hardware, firmware, software, or a combination thereof.

In a hardware configuration, the methods according to exemplaryembodiments of the present disclosure may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the methods according to theembodiments of the present disclosure may be implemented in the form ofa module, a procedure, a function, etc. performing the above-describedfunctions or operations. A software code may be stored in the memory 50or 150 and executed by the processor 40 or 140. The memory is located atthe interior or exterior of the processor and may transmit and receivedata to and from the processor via various known means.

Those skilled in the art will appreciate that the present disclosure maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent disclosure. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of thedisclosure should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein. It is obvious to those skilled in the art thatclaims that are not explicitly cited in each other in the appendedclaims may be presented in combination as an embodiment of the presentdisclosure or included as a new claim by a subsequent amendment afterthe application is filed.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to various wireless access systemsincluding a 3GPP system, and/or a 3GPP2 system. Besides these wirelessaccess systems, the embodiments of the present disclosure are applicableto all technical fields in which the wireless access systems find theirapplications. Moreover, the proposed method can also be applied tommWave communication using an ultra-high frequency band.

1. A method of transmitting and receiving a signal to and from a basestation (BS) by a user equipment (UE) in a wireless communicationsystem, the method comprising: receiving, from the BS, a signal composedof at least one code block group (CBG); and transmitting, to the BS,acknowledgement (ACK) information for each CBG, wherein the ACKinformation includes a plurality of numbers of bit information, whereineach CBG comprises at least one code block (CB), wherein the pluralityof numbers of the bit information indicates one of states among onestate for indicating ACK and N states for indicating non-acknowledgement(NACK), where N is a natural number larger than 1, and wherein each ofthe N states indicates a combination of at least one of: firstinformation indicating whether a number of CBs where the NACK occurs ina corresponding CBG is greater than or equal to a predetermined value,and whether, when the number of the CBs where the NACK occurs is greaterthan or equal to the predetermined value, there are consecutive CBsamong the CBs where the NACK occurs; second information indicating alocation region including the CBs where the NACK occurs in thecorresponding CBG; third information indicating a range including aratio of the CBs where the NACK occurs to whole CBs included in thecorresponding CBG; and fourth information indicating a retransmissionmethod preferred by the UE for the corresponding CBG.
 2. The method ofclaim 1, wherein the first information indicates one of: informationindicating that the number of the CBs where the NACK occurs in thecorresponding CBG is smaller than or equal to the predetermined value;information indicating that the number of the CBs where the NACK occursin the corresponding CBG is greater than the predetermined value and theCBs where the NACK occurs are not consecutive; and informationindicating that the number of the CBs where the NACK occurs in thecorresponding CBG is greater than the predetermined value and theconsecutive CBs are present among the CBs where the NACK occurs.
 3. Themethod of claim 1, wherein the second information indicates one of:information indicating that among first and second CBGs obtained bydividing the corresponding CBG in half, the first CBG includes at leastone CB where the NACK occurs; information indicating that among thefirst and second CBGs obtained by dividing the corresponding CBG inhalf, the second CBG includes at least one CB where the NACK occurs; andinformation indicating that both the first and second CBGs obtained bydividing the corresponding CBG in half include at least one CB where theNACK occurs.
 4. The method of claim 1, wherein the third informationindicates one of: information indicating that the ratio of the CBs wherethe NACK occurs to the whole CBs included in the corresponding CBG issmaller than or equal to a first threshold; information indicating thatthe ratio of the CBs where the NACK occurs to the whole CBs included inthe corresponding CBG is greater than the first threshold and smallerthan or equal to a second threshold; and information indicating that theratio of the CBs where the NACK occurs to the whole CBs included in thecorresponding CBG is greater than the second threshold.
 5. The method ofclaim 1, wherein the fourth information indicates one of: informationindicating that the retransmission method preferred by the UE for thecorresponding CBG is an incremental redundancy (IR) type; andinformation indicating that the retransmission method preferred by theUE for the corresponding CBG is a chase combining (CC) type.
 6. Themethod of claim 1, further comprising: some CBs in the received signalcomposed of the at least one CBG are dropped by the BS, receivinginformation on the dropped CB s from the BS.
 7. The method of claim 6,wherein when the some CBs in the received signal composed of the atleast one CBG are dropped by the BS, the UE determines the N states byexcluding the dropped CBs from counting or assuming the dropped CBs asthe ACK.
 8. The method of claim 1, further comprising: receiving, fromthe BS, a response message in response to the ACK information for eachCBG.
 9. The method of claim 8, wherein the response message comprises:retransmission of whole CBs included in a CBG reported by the UE as theNACK; or retransmission of some CBs included in the CBG reported by theUE as the NACK.
 10. The method of claim 8, wherein when some CBs in thereceived signal composed of the at least one CBG are dropped by the BS,the response message comprises retransmission of the some CBs includedin a CBG reported by the UE as the NACK.
 11. The method of claim 8,further comprising: transmitting, to the BS, ACK information for atleast one CBG included in the response message.
 12. A method oftransmitting and receiving a signal to and from a user equipment (UE) bya base station (BS) in a wireless communication system, the methodcomprising: transmitting, to the UE, a signal composed of at least onecode block group (CBG); and receiving, from the UE, acknowledgement(ACK) information for each CBG, wherein the ACK information includes aplurality of numbers of bit information, wherein each CBG comprises atleast one code block (CB), wherein the plurality of numbers of the bitinformation indicates one of states among one state for indicating ACKand N states for indicating non-acknowledgement (NACK), where N is anatural number larger than 1, and wherein each of the N states indicatesa combination of at least one of: first information indicating whether anumber of CBs where the NACK occurs in a corresponding CBG is greaterthan or equal to a predetermined value and whether, when the number ofthe CBs where the NACK occurs is greater than or equal to thepredetermined value, there are consecutive CBs among the CBs where theNACK occurs; second information indicating a location region includingthe CBs where the NACK occurs in the corresponding CBG; thirdinformation indicating a range including a ratio of the CBs where theNACK occurs to whole CBs included in the corresponding CBG; and fourthinformation indicating a retransmission method preferred by the UE forthe corresponding CBG.
 13. A user equipment (UE) for transmitting andreceiving a signal to and from a base station (BS) in a wirelesscommunication system, the UE comprising: a transmitter; a receiver; anda processor connected to the transmitter and the receiver, wherein theprocessor is configured to: receive, from the BS, a signal composed ofat least one code block group (CBG); and transmit, to the BS,acknowledgement (ACK) information for each CBG, wherein the ACKinformation includes a plurality of numbers of bit information, whereineach CBG comprises at least one code block (CB), wherein the pluralityof numbers of the bit information indicates one of states among onestate for indicating ACK and N states for indicating non-acknowledgement(NACK), where N is a natural number larger than 1, and wherein each ofthe N states indicates a combination of at least one of: firstinformation indicating whether a number of CBs where the NACK occurs ina corresponding CBG is greater than or equal to a predetermined valueand whether, when the number of the CBs where the NACK occurs is greaterthan or equal to the predetermined value, there are consecutive CBsamong the CBs where the NACK occurs; second information indicating alocation region including the CBs where the NACK occurs in thecorresponding CBG; third information indicating a range including aratio of the CBs where the NACK occurs to whole CBs included in thecorresponding CBG; and fourth information indicating a retransmissionmethod preferred by the UE for the corresponding CBG.
 14. A base station(BS) for transmitting and receiving a signal to and from a userequipment (UE) in a wireless communication system, the BS comprising: atransmitter; a receiver; and a processor connected to the transmitterand the receiver, wherein the processor is configured to: transmit, tothe UE, a signal composed of at least one code block group (CBG); andreceive, from the UE, acknowledgement (ACK) information for each CBG,wherein the ACK information includes a plurality of numbers of bitinformation, wherein each CBG comprises at least one code block (CB),wherein the plurality of numbers of the bit information indicates one ofstates among one state for indicating ACK and N states for indicatingnon-acknowledgement (NACK), where N is a natural number larger than 1,and wherein each of the N states indicates a combination of at least oneof: first information indicating whether a number of CBs where the NACKoccurs in a corresponding CBG is greater than or equal to apredetermined value and whether, when the number of the CBs where theNACK occurs is greater than or equal to the predetermined value, thereare consecutive CBs among the CBs where the NACK occurs; secondinformation indicating a location region including the CBs where theNACK occurs in the corresponding CBG; third information indicating arange including a ratio of the CBs where the NACK occurs to whole CBsincluded in the corresponding CBG; and fourth information indicating aretransmission method preferred by the UE for the corresponding CBG. 15.The UE of claim 13, wherein the UE communicates with at least one of amobile terminal, a network and an autonomous vehicle.